Apparatus and method for generating high-intensity light



Dec. 24, 1968 F, WALTER ET AL 3,418,524

APPARATUS AND METHOD FOR GENERATING HIGH-INTENSITY LIGHT 46, INVENToRs.

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WAL TER PQDOL SK Y United States Patent O 3,418,524 APPARATUS AND METHOD FOR GENERATING HIGH-INTENSITY LIGHT Fred Walter, Newport Beach, Calif., and Boris Podolsky,

Cincinnati, Ohio, assignors to Giannini Scientific Corporation, Amityville, N.Y., a corporation of Delaware Filed Nov. 29, 1965, Ser. No. 510,292 23 Claims. (Cl. 315-111) ABSTRACT F THE DISCLOSURE A vortex-stabilized radiation source in which a shroud is provided coaxially around at least one of the opposed electrodes between which the electrical discharge is effected. In accordance with one embodiment, vorticallyflowing gas from the vicinity of the arc is drained through the shroud. In accordance with another embodiment, vortically-owing gas is introduced through the shroud into the discharge chamber.

This invention relates to an apparatus and method for generating light, and more particularly to a vortex-stabilized radiation source wherein shroud means are provided for at least portions of the electrode means between which the electrical discharge is effected.

It has ben discovered by prior workers in the field of vortex-stabilized light (radiation) sources that surprising and important advantages are achieved by effecting discharge of the vortically-flowing arc gas at at least one region which is relatively adjacent one of the footpoints or terminals of the arc. The advantages relate to such factors as degree of arc constriction, arc stability, character of the radiation, electrode life, etc. In a basic construction of the indicated type, the arc gas was shown as discharging through an axial bore in at least one of the opposed electrodes.

In view of the above, it is a primary object of the present invention to provide an apparatus and method for generating light (including ultraviolet and infrared radiation) by means of a vortex-stabilized radiation source of the type wherein gas discharges adjacent an arc footpoint, and which achieves a higher degree of luminous efliciency than is achieved by radiation sources wherein the only gas-discharge outlet is through an axial bore in an electrode.

Another object is to provide a radiation source wherein arc gas flows through a shroud encompassing at least one of the electrode arcing portions.

Another object is to provide a vortex-stabilized radiation source having solid electrodes.

Another object of the invention is to provide an apparatus and method for generating light through use of vortically-owing pure arc gas, such as xenon, argon, krypton, etc., which is free of additive substances.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a View, primarily in longitudinal section, illustrating schematically one form of vortex-stabilized radiation source incorporating the present invention;

FIGURE 2 is an enlarged fragmentary view illustrating the central region of the showing of FIGURE 1;

FIGURE 3 is a transverse sectional view on line 3-3 of FIGURE 2;

FIGURE 4 is a transverse sectional View on line 4-4 of FIGURE 2;

FIGURE 5 is a fragmentary horizontal sectional View taken on line 5-5 of FIGURE 4;

FIGURE 6 is a fragmentary view illustrating a second CFI ICC

embodiment of the invention, wherein the gas is introduced through a shroud into the arc chamber; and

FIGURE 7 is a view corresponding generally to FIG- URE 1 but illustrating schematically a third embodiment -of the invention, in which the arc gas is discharged through a shroud which surrounds the cathode of the radiation source.

Referring iirst to the embodiment of FIGURES 1-5, inclusive, the Vortex-stabi-lized radiation source is illustrated to comprise outer and inner elongated tubular envelopes 10 and 11, respectively, which are mounted coaxially of each other and in radially-spaced relationship whereby an annulus 12 is defined therebetween. The envelopes may be formed of fused silica, quartz, lor other suitable transparent substance. The envelopes are mounted in the described relationship by means of metallic end elements or head elements, which are indicated at 13 and 14. As will be described in detail subsequentially, such end elements also perform the very important function of supporting the critical electrode and shroud structures of the present invention. Except as will be specifically indicated, the elements 13 and 14 are formed of copper, brass, or other conductive metals.

The end or head element 13, indicated at the left in FIGURE 1, comprises an outer portion 16 which receives the ends of envelopes 10 and 11, and an inner or stem portion 17 which is cylindrical in shape and extends inwardly in surface abutment with the interior cylindrical surface of envelope 11. Stem portion 17 is hollow, incorporating a chamber 18 adapted to receive coolant and also adapted to receive portions of electrode and other structures.

An elongated electrode 19 is mounted at the inner end of the stem portion 17. More specically, the electrode 19 has-a hollow cylindrical body Which fits closely within a bore 21 which is provided at the inner end of the stem 17, coaxially of envelopes 10 and 11. At the inner end of the electrode is a generally conical portion 22 the axis of which is coincident with the axis of the arc chamber 23 defined within inner envelope 11. At the outer end of the electrode 19 is a radial portion 24 which is disposed at the inner end of the chamber 18. In the illustrated construction, the inner end of conical portion 22 is shown as comprising a generally lrounded or hemispherical inert 26 which may be formed of tungsten, thoriated tungsten, etc.

The regions of electrode 19 to the left of insert 26, as viewed in FIGURES 1 and 2, receive two concentric tubular conduit elements 27 and 28. The first such conduit, number 27, is relatively small in diameter and extends through chamber 18, axially of electrode 19, to a bore or chamber 29 formed within conical electrode'portion 22. Such bore or chamber 29 communicates radially, as through four radial passages indicated at 31, with a region surrounding conical electrode portion 22. Thus, the conduit 27, bore or chamber 29 `and radial passages 31 form part of the highly important gas flow system to be described in detail below.

It s to be understood that suitable sealing means may be provided around the inner end of conduit 27, to prevent any possibility of leakage of water and/ore gas between chamber 29 and the relatively large counterbore or recess which is formed in electrode 19 to the left of chamber 29.

The second conduit, number 28, is relatively large in diameter and is mounted in concentric, outwardly-spaced relationship relative to the first-mentioned conduit 27. Conduit 28 is suitably mounted to the end wall 16 of end or head element 13, and may be termed a water separator since it guides the flow of water or other coolant through the chamber 18 and through regions of the electrode 19.

As indicated schematically in FIGURE 2, water may be introduced continuously through a conduit 32 into the region of chamber 18 radially-outwardly of the water separator 28. The water then ows to the right, passing between the outer surface of the separator and the internal surface of electrode 19 (which surface is spaced radially-outwardly from the outer separator surface). The water then passes around the inner end of the separator, following which it flows to the left through the annulus between conduits 27 and 28 for discharge through a conduit 33. The electrode 19 is thus etfectively and continuously cooled.

Proceeding next to a description of Ia major element of the invention, a shroud 36 is mounted in arc chamber 23 coaxially around electrode portion 22 and insert 26. In the illustrated embodiment, the outer end of shroud 36 is suitably secured, as by brazing, to the stem 17 of element 13.

The illustrated shroud 36 has a frustoconical exterior surface 37 and a frustoconical interior surface 38. Surface 38 merges, at a region radially-outwardly from insert 26, with a cylindrical surface portion 39 which extends to the extreme inner end of the shroud. The diameters of surface Iportion 39 and internal surface 38 are sufficiently great that an annulus 41 is deiined around the electrode. Such annulus serves to conduct vortically-flowing gas from arc chamber 23 to the outer ends of the above-indicated radial passages 31. The outer passage ends are preferably ared, as shown in FIGURES 2 and 3.

The extreme inner end of shroud 36 is shown as penetrating a lesser distance into arc chamber 23 than does the extreme inner end of the electrode insert 26. Stated otherwise, the shroud is cut back relative to the arcing end portion of the electrode. The function of the shroud will be set forth in detail hereinafter.

There will next be described the rem-aining end or head element, number 14, which is illustrated to comprise an outwardly-facing cup member 42 having an inwardly-extending stem or base portion 43. Outer envelope seats at one edge of the main body of the cup member 42, whereas inner envelope 11 seats around the inner end of stem 43. A portion of stem 43 between such inner end and the m-ain body of the cup is provided with an annular groove 44 adapted to be employed in passing gas from annulus 12 to arc chamber 23. Such gas passes from the groove 44 through -a plurality of passages 46 which are oriented generally tangentially relative to the arc chamber 23. Passages 46 also extend somewhat axially in order that the gas introduced therethrough into the arc chamber will iiow in a generally helical manner to annulus 41 and thence out through passages 31 and conduit 27.

The cup member 42 and its associated stern or base portion 43 Iare provided with an |axial bore to receive the remaining electrode, number 47, of the apparatus. Such electrode is shown as having an elongated, generally cylindrical main body which is inserted through the indicated bore in close-fitting relationship, terminating at its inner end in a conical portion 48 at the apex region of which is provided an insert 49. Insert 49, which may be formed of tungsten, thoriated tungsten, etc., has a generally conical body which is coaxial with the arc ch-amber 23. A generally cylindrical arcing portion 51 is formed at the extreme apex end of the insert 49 and has a conical tip as illustrated. Arcing portion 51, and arcing portion or insert 26 of the electrode 19, lie along the common axis of arc chamber 23 and of envelopes 10 and 11.

The electrode 47 also has a radially-extending base portion 52 which is threadedly associated with cup member 42, completely filling the recess defined by such cup member. An end cap 53 is also threaded over base portion 52 and defines a chamber 54 into which water or other coolant may be discharged from an axial bore 56 inthe electrode 47. Water is passed continuously into the inner end of bore 56 by means of a conduit 57 which extends into such bore coaxially thereof and in radially-spaced rela- Cil tionship relative to the Wall of the bore. The water then flows through the annulus around conduit 57, following which it ows through chamber 54 and then discharges or drains through a second conduit indicated at 58. Thus, the electrode 47 is also effectively cooled.

It is emphasized that because the arcing portion 51 of the electrode 47 is relatively small in diameter, and a considerable distance from the coolant chamber within the electrode, such arcing portion is caused to operate at a relatively elevated temperature (frequently at or near the melting point thereof). This has been found to improve the stability, eciency Iand light-generation characteristics of the radiation source.

It is to be understood that various O-rings and other suitable seals are provided lat different portions of the source in order to prevent undesired leakage of fluids between adjacent chambers and passages. Only some of such sealing elements are `illustrated in the drawings.

The gas-recirculation system for the present radiation source comprises a suitable heat exchanger 59 into which hot gas is introduced from conduit 27, such heat exchanger serving to cool the gas and discharge the same to a recirculation pump schematically represented Iat 60. From pump 60, the gas ows through a conduit 61 into the left end (FIGURE l) of the annulus 12 between envelopes 10 and 11. The gas then passes through such annulus to the annular groove 44, and thence through the tangentially-oriented passages 46 to the region of arc chamber 23 radially-outwardly of electrode 47. Thereafter, the gas iiows generally vortically or helically in chamber 23, about the common axis of electrode arcing regions 26 and 51, for discharge as labove indicated through shroud annulus 41, passages 31 and conduit 27.

A power source, indicated schematically at 62 in FIG- URE 1, is connected through a lead 63 to cup member 42, and through a lead 64 to the end or head element 13. The power source 62 should be a D.C. source adapted to deliver a high current, such as on the order of hundreds of amperes, to the connected members and thus to the electrodes 19 and 47. The power source should be so connected, in the present embodiment, that the positive terminal thereof is associated through lead 64 with electrode 19 which therefore forms the anode of the radiation source. Lead 63 is connected to the negative source terminal, so that electrode 47 forms the cathode.

METHOD, EMBODIMENT OF FIGURES 1-5 Stated generally, the method comprises effecting gasvortex stabilization of an electrical discharge, normally a sustained electric arc, by means of gas iiowing through an arc chamber having a transparent wall portion, and draining vortically-flowing gas through a shroud disposed around one of the electrodes between which the electrical discharge is maintained. Stated more specifically, the method additionally comprises maintaining the vortexstabilized discharge between fully-exposed arcing portions of opposed electrodes at least one of which is shrouded, and transmitting light from the fully-exposed discharge through a transparent wall portion of the arc chamber.

With particular reference to the apparatus illustrated in FIGURES l-S, the method comprises eliminating all air from the passages and chambers within the gas recirculation system of FIGURE 1, and filling such system with a desired inert arc gas such as xenon, argon, kryptom neon, etc. Pump 60 is then started to effect ow of the gas through conduit 61 into annulus 12 between envelopes 10 and 11, thence through annular groove 44 and tangentially-arranged passages 46 into arc chamber 23 for vorti- .cal flow therein, and thence through annulus 41 and radial passages 31 into conduit 27 for recirculation back to the heat exchanger 59 and pump 60. The gas should be under relatively high pressure, for example hundreds of pounds per square inch.

Power source 62 is then applied, and a suitable means (such as a momentary pulse of high voltage) is employed to initiate an electric arc between the central arcing portion of insert 26 and the arcing portion (end of cylinder 51) of insert 49.

The vertically-flowing gas in arc chamber 23 stabilizes and constricts the arc or discharge, which is indicated at 67 in FIGURES l and 2, so that such discharge is relatively small in diameter despite the fact that the direct current delivered from power source 62 should be relatively high, for example hundreds of amperes. The combination of the high-current electric arc, and the bleedingoff through annulus 41 of the hot boundary layer of gas at a region adjacent electrode 19 and closely adjacent the arc, causes the emission of desired radiation from the arc 67 to be very great.

The draining of gas through the annulus 41 defined within shroud 36 provides a much stronger arc-constricting and arc-stabilizing effect than would be the case if the gas were drained at a region which is axially-spaced from the discharge, for example adjacent the base of a relatively long inwardly-protruding electrode. `Because the region radially-outwardly of shroud 36 is part of the vortex chamber 23, and surrounded by a portion of the transparent envelope 11, there is relatively little blocking of light generated yby the arc 67. This is particularly true because the arcing regions of both electrodes are fully exposed, thus permitting radiation from all portions of the arc (including the footpoints) to Ibe transmitted directly through the envelopes and 11.

The electrodes are maintained sufiiciently cool to prevent excessive melting thereof by means of water which is circulated through the above-described conduits 32-33 and 57-58, and thus through the electrodes. As previously indicated, the cathode region 51 should be sufficiently long and remote from the adjacent water chamber or bore 56 that it operates (at least at the extreme end) in molten or near-molten condition. It is pointed out that the cathode tends, because of electron evaporation therefrom, to remain much cooler than the anode.

EMBODIMENT OF FIGURE 6 The embodiment of FIGURE 6 is identical to that described relative to FIGURES 1-5, except that gas is introduced into the vortex chamber 23 through a shroud surrounding one of the electrodes. In the illustrated form, the gas is introduced through a shroud 68 surrounding cathode 47, but it is to be understood that the gas may be introduced through a shroud surrounding the anode and then discharged through a shroud surrounding the cathode as will ybe indicated realtive to te embodiment of FIGURE 7. Furthermore, gas may vbe introduced tangentially independently of various shrouds, and then discharged through a shroud (or shrouds) surrounding one (or both) of the electrodes.

The shroud 68 is a generally frustoconical metal member having a base end 69 seated radially-outwardly of the inlet ends of the tangential passages 46 through which the gas is introduced as described in detail above. Thus, the gas enters into the Ibase of the shroud instead of into the end of the arc chamber 23. The shroud 68 also has an apex end or annular lip 70 disposed radially-outwardly of the end portion 51 of cathode insert 49.

In the method relative to the embodiment of FIGURE 6, the gas is introduced tangentially into the shroud base for vortical flow around electrode 47, following which the gas discharges through the apex region 70 for vortical flow in arc chamber 23. Thereafter, the vertically-flowing gas discharges through the above-indicated annulus 41 around anode 19.

It is emphasized that the gas thus introduced into the arc chamber is relatively cool and has a well-defined vortical motion, not a relatively random or turbulent motion.

EMBODIMENT OF FIGURE 7 Except as specifically stated below, the embodiment of FIGURE 7 is identical to that of FIGURES 1-5. In

those instances where the elements are similar |but not identical to those previously described, the same reference numerals have been used except followed in each instance by the letter a.

In the embodiment of FIGURE 7, the negative ter minal of power source 62 is connected through a lead 76 with the end or head element 13. Conversely, the positive terminal of such power source is connected through a lead 77 to the end or head element 14. Thus electrode 19a is caused to be the cathode and electrode `47a the anode.

The electrodes 19a and 47a are provided, respectively, =with suitable tungsten inserts 78 and 79 having arcing portions disposed opposite each other coaxially of the chamber 23. Such inserts are illustrated as being generally conical in shape.

The method of the embodiment of FIGURE 7 is the same as that previously described except that verticallyflowing gas is drained (discharged) adjacent the cathode insert 78 as distinguished from adjacent the anode. Such discharge of gas adjacent the cathode is advantageous in many cases because the cathode tends to operate at a relatively low temperature, as indicated above, due to electron evaporation to the anode. Thus, and despite the fact that the discharging gas is extremely hot, the cathode does not become excessively hot and therefore has a relatively long life.

It is pointed out that, relative to all embodiments, the recirculating gas Should be clean and pure. The presence of impurities, additives, etc., in the gas may effect clouding ofthe envelope and other undesired effects.

SPECIFIC EXAMPLE There will next be given, for purposes of illustration and not limitation, a specific example relative to one embodiment of the invention. Relative to the embodiment of FIGURES 1-5, the diameter of inner envelope 11 may be 21.2 millimeters, the distance from insert 26 to insert 51 may be 8 millimeters, and the gas employed may be argon at a pressure within chamber 23 of 200 p.s.i. gauge. Power source 62 may deliver 20G-250 amperes at a voltage of 25-35 volts.

The diameter of each of the four illustrated gas inlets 46 (FIGURE 4) may be 1 millimeter, whereas the diameter of the minimum-diameter (not flared) portions of each of the four radial passages 31 (FIGURE 3) may be 1 millimeter.

The rate of gas recirculation may be l.5-2 standard cubic feet per minute.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

We claim:

1. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a major portion of said wall means being formed of transparent material,

a first electrode arcing portion disposed in said chamber in inwardly-spaced relationship from said wall means,

a second electrode arcing portion disposed opposite said first electrode arcing portion and in spaced relationship therefrom,

means to define a surface generally surrounding at least said first electrode arcing portion and through which gas may be drained from said chamber,

said surface-dening means being disposed in said chamber in inwardly-spaced relationship from said wall means,

said surface-defining means being a shroud disposed in said chamber generally-coaxially of said first electrode arcing portion and encompassing at least a major part thereof,

means to introduce gas continuously into said chamber in such manner that said gas will flow vortically therein about an axis extending between said first and second electrode arcing portions, i

means to drain gas from said chamber through said shroud, and

means to effect an electrical discharge in said chamber between said first and second electrode arcing portions.

2. The invention as claimed in claim 1, in which said first electrode arcing portion is protuberant from the inner end of said shroud, whereby the radiation generated at said first electrode arcing portion is substantially unshielded by said shroud.

3. The invention as claimed in claim 1, in which said gas-introduction means introduces a substantially pure inert gas which is free of additives.

4. The invention as claimed in claim 1, in which both of said arcing portions are free of substantial recesses and passages.

5. Apparatus for generating high-intensity light, which comprises:

wall means to define an arc chamber,

at least a major portion of said wall means being a surface of revolution about a central axis,

at least a major portion of said wall means being formed of transparent material,

a first electrode arcing portion disposed in said chamber in inwardly-spaced relationship from all portions of said wall means,

a second electrode arcing portion disposed in said charnber in inwardly-spaced relationship from all portions of said wall means,

said first and second electrode arcing portions being disposed along said axis in spaced relationship from each other,

means to define a surface generally surrounding at least said first electrode arcing portion and through which gas may be drained from said chamber,

said surface-defining means being a shroud disposed in said chamber in inwardly-spaced relationship from all portions of said wall means, said shroud being coaxial with said axis,

means to introduce gas continuously into said chamber in generally tangential relationship relative thereto whereby said gas fiows vortically in said chamber about said axis, means to drain gas from said chamber through said shroud, and

means to maintain a high-current electric arc in said chamber between said first and second electrode arcing portions.

6. The invention as claimed in claim 5, in which means are provided to define a surface generally surrounding said second electrode arcing portion and through which gas may fiow between said chamber and a region external to said chamber, said last-named surface-defining means being coaxial with said axis.

7. A high-intensity light source, which comprises:

an elongated tubular envelope formed of transparent material,

end-wall means disposed at each end of said envelope to close the same and thereby define an arc chamber within said envelope,

first and second elongated metal electrodes extended, re-

spectively, through said end-wall means coaxially of said envelope and terminating at their inner ends in arcing portions which are spaced from each other along the axis of said envelope,

a shroud disposed within said chamber coaxially around said first electrode,

said shroud having a generally frustoconical interior surface spaced radially-outwardly from said first electrode to define an annulus therebetween,

the inner end of said shroud being disposed radiallyoutwardly from the arcing portion of said first electrode,

the outer end of said shroud connecting with the end-wall means through which said first electrode extends,

means to drain gas from said annulus defined between said shroud and said first electrode,

means to introduce gas generally tangentially into said envelope for vortical fiow therein, and

means to maintain an electrical discharge along said axis between said arcing portions of said electrodes.

8. The invention as claimed in claim 7, in which said gas-introduction means includes an inlet in the end-wall means through which said second electrode extends.

9. The invention as claimed in claim 7, in which said means to maintain said discharge includes a D C. power source, in which the positive terminal of said source is connected to said second electrode, and in which the negative terminal of said Asource is connected to said first electrode, whereby said discharge is a direct current electric arc and whereby said first electrode is the cathode.

10. The invention as claimed in claim 7, in which said means to maintain said discharge includes a D.C. power source, in which the positive terminal of said source is connected to said first electrode, and in which the negative terminal of said source is connected to said second electrode, whereby said discharge is a direct current electric arc and whereby said first electrode is the anode.

11. The invention as claimed in claim 7, in which said inner end of said shroud is disposed closer to the end-wall means through which said first electrode projects than is said arcing portion of said first electrode, whereby said arcing portion of said first electrode is exposed directly to said tubular envelope for radiation of light therethrough.

12. The invention as claimed in claim 7, in which a second shroud is mounted coaxially around said second electrode and within said chamber.

13. The invention as claimed in claim 7, in which the axial portion of the arcing end of at least one of said first and second electrodes is free of passages or recesses.

14. The invention as claimed in claim 7, in which means are provided to circulate coolant through said first and second electrodes for cooling thereof.

15. A high-intensity light source, which comprises:

Wall means to define an arc chamber the major wall portion of which is a surface of revolution about a central axis,

at least a substantial portion of said wall means being formed of transparent material whereby to transmit radiation out of said chamber, first and second electrodes disposed in said chamber and having arcing portions disposed along said axis in spaced relationship from each other,

a shroud provided in said chamber coaxially around said first electrode,

a D.C. current source,

means to connect the positive terminal of said D.C.

source to said first electrode and the negative terminal of said source to said second electrode,

means to introduce gas generally tangentially into said chamber at a region surrounding said second electrode, and

means to drain gas from said chamber through a region between said first electrode and said shroud encompassing the same.

16. A high-intensity light source, which comprises:

wall means to define an arc chamber the major wall :portion of which is a surface of revolution about a central axis,

at least a substantial portion of said wall means being formed of transparent material whereby to transmit radiation out of said chamber,

first and second electrodes disposed in Said chamber and having arcing portions disposed along said axis in spaced relationship from each other,

a shroud provided in said chamber coaxially around said first electrode,

a D.C. current source,

means to connect the negative terminal of said D.C.

source to said first electrode and the positive terminal of said source to said second electrode, means to introduce gas generally tangentially into said chamber at a region surrounding said second electrode, and

means to drain gas from said chamber through a region between said first electrode and said shroud encompassing the same.

17. A high-intensity radiation source, which comprises:

wall means to define an elongated arc chamber,

at least a major portion of said wall means being a surface of revolution about the axis of said chamber,

at least a major portion of said wall means being formed of transparent material for transmission of radiation from said chamber to a desired region,

first and second electrodes extending into opposite ends of said chamber and having arcing portions disposed in spaced relationship from each other along the axis of said chamber,

first and second shrouds mounted, respectively, around said first and second electrodes and coaxially of said chamber,

the inner surfaces of said shrouds being spaced radially-outwardly from the corresponding exterior surfaces of said first and second electrodes whereby to form gas-How passages between said shrouds and the electrodes encompassed thereby, means including the passage between at least one of said shrouds and the associated electrode to effect vortical flow of gas in said chamber about said axis, and means to maintain a high-current electric are between said arcing portions and along said axis.

18. The invention as claimed in claim 17, in which said gas-flow means includes means to introduce gas generally tangentially into the outer end of one of said shroud passages for vortical flow around the electrode encompassed thereby, and further includes means to drain gas from said chamber through the other of said shroud passages.

19. The invention as claimed in claim 17, in which said shrouds and electrodes have generally conical regions adjacent each other, and in which said shroud passages are annuluses the diameters of which decrease in directions toward the space between said arcing portions.

20. A high-intensity light source, comprising:

wall means to define an arc chamber,

at least a major portion of said wall means being formed of transparent material whereby to transmit light from said chamber to a desired region,

first and second electrodes extended into said chamber and having arcing portions disposed opposite each other in said chamber,

means to supply current to said electrodes to thereby effect an electrical discharge in said chamber between said arcing portions,

a shroud mounted around one of said electrodes in said chamber,

means to introduce gas generally tangentially into said shroud for vortical flow around said one electrode and thence into said chamber, and

means to drain gas from said chamber.

21. A method of generating high-intensity light, which comprises:

defining an arc chamber,

disposing a first electrode arcing portion in said chamber in inwardly-spaced relationship from the wall thereof,

disposing a second electrode arcing portion in said chamber in spaced relationship from said first electrode arcing portion,

introducing gas continuously into said chamber in such manner that said gas will flow vortically therein about an axis extending between said first and second electrode arcing portions,

draining gas continuously from said chamber through a shroud encompassing said first electrode arcing portion,

maintaining a high-current electrical discharge between said electrode arcing portions and along said axis, and transmitting light from said discharge to a region exterior to said chamber and along a path independent of the gas-introduction and gas-drainage paths for said gas.

22. The invention as claimed in claim 21, in which said gas is selected from a group consisting of argon, xenon, krypton, neon, and mixtures thereof.

23. The invention as claimed in claim 21, in which said method includes maintaining said discharge by means of a D.C. power source and by passing current through said electrodes in the range of hundreds of amperes, and in which said method further comprises maintaining the gas pressure within said chamber in the range of hundreds of p.s.1.

References Cited UNITED STATES PATENTS 3,064,153 11/1962 Gage 315-111 X 3,172,000 3/1965 Rosener et al 313-231 X 3,255,379 6/1966 Miller 313-231 X 3,292,028 12/ 1966 Van Ornum 313-231 X FOREIGN PATENTS 681,349 10/ 1952 Great Britain.

JAMES W. LAWRENCE, Primary Examiner.

P. C. DEMEO, Assistant Examiner.

U.S. C1. X.R. 313--231 

